At the 2016 Finningley Rally i Spotted some analogue ATV Transmitters made by Gigawave, various frequency versions were available.
I mentioned the 6cm version to Clive G4FVP and he snapped one up quickly to use on GB3KM's new 6cm input.

The Tx generates ~1W and has 16 pre-set channels and fixed 6.8/7.5MHz audio frequencies.

I have managed to re-program the Tx frequency specifically for GB3KM's input on 5.665GHz, and set the two audio channels, now on 6.0MHz and 7.5MHz.
The Tx PLL is an MB1508
The audio PLL's are MB87001
Model is: Gigawave TX 5.5 P

Here is a Link to the Arduino code for 5.665MHz RF and 6.0MHz/7.5MHz Sound.

Connections for the Arduino SPI interface are here:
I cut the tracks between the marked connection pads and the original PIC IC.

SPI connections

VCO and PIC Control side (inc test wires)

Audio Channel side